To be honest, I really love my rMBP 2014 hardware, it was basically perfect. Great speaker, as you say, good enough keyboard, BEST display, etc.
If Apple releases another MBP based on 2015 I'll take a quite good look again.
Of course it would be nicer if the laptop had better speakers in it, but there are always trade-offs to be made on cost vs benefit, and fairly cheap bluetooth speakers are a pretty good workaround for a lot of people.
What I'm trying to say is that if really good audio quality is important to you, then having a couple of sets of bluetooth speakers in your house strategically placed in the places where you'd regularly watch movies or consume other high-quality audio is a reasonable workaround for a lot of people. OF COURSE having better speakers (equivalent in sound quality to the bluetooth workaround) in your laptop would be better if you care a lot about audio quality. But that would add to the cost of the laptop for every user, even the ones that don't care about having really high-quality audio on their laptop. I'm saying that it's not unreasonable for a manufacturer to make some tradeoffs like that when there are workarounds that work fairly well.
Over time the costs of adding higher-end features like this drop, and things like audio quality improve to the point that the workarounds aren't needed (the audio quality of my phone speaker is actually pretty amazing).
The better speakers I'd like. I still need to use USB sticks and SD pretty frequently and have always hated bags of adaptors. They always seem to break or get lost at the moment you're sitting with the important client.
The rest seems to come with a cost far worse than the benefit (for me anyway).
Larger trackpad was so large I would constantly get false activations when typing. Perhaps I have the wrong sort of fingers.
The touchbar was constantly activating when I typed on the top row of physical keys. Perhaps I have the wrong sort of fingers again. :)
The newer thinner keyboard was both horrible and horribly unreliable. Dust sensitive? LOL I think back to when the kids were little and throwing rusks, or putting toast in the VCR the moment we blinked. Then the amount of dog and cat hair (that magically gets everywhere) that's been removed from our keyboards over the years.
Lighter is OK, but not at a huge battery life cost compared to the 2015.